EFFECT OF SUPPLEMENTARY CHELATED ZINC AND MANGANESE METHIONINE ON PRODUCTIVE AND REPRODUCTIVE PERFORMANCE OF FRIESIAN COWS

Abstract

This study aimed to investigate the effect of adding chelated zinc or/and manganese methionine on productive and postpartum reproductive traits. Twenty lactating Friesian cows with an average live body weight of 500 kg and on 2-4 seasons of lactation were used after calving immediately and divided into four similar groups (5 each) and assigned randomly into four treatments of feeding trial. Cows were fed a basal ration that consisted of 40% concentrate feed mixture (CFM), 40% fresh berseem (FB) and 20% rice straw (RS), on a dry matter basis. The 1st group was unsupplemented and served as control (T1), while 2nd, 3rd and 4th groups were supplemented (per/head/day) with zinc methionine (ZINPRO) 100 mg Zn (T2) or manganese methionine (MANPRO) 100 mg Mn (T3) and 50 mg Zn + 50 mg Mn (T4). Results indicated that the digestibility of all nutrients, as well as feeding values, increased significantly (P<0.05) with zinc and manganese methionine supplemented treatments than control. Daily intake was significantly higher (P<0.05) in T2 compared to T1. Total volatile fatty acids (TVFA’s) concentration increased significantly (P<0.05), however, ammonia nitrogen (NH3-N) decreased significantly (P<0.05) with chelated zinc and manganese supplements in comparison with control (unsupplemented one). Plasma total protein and globulin concentrations increased significantly (P<0.05), however, AST and ALT enzymes activity decreased significantly (P<0.05) with chelated zinc and manganese supplements. Also, actual milk and 4% fat corrected milk (FCM) yield and the contents of fat, protein, lactose, solids not fat and total solids in milk were increased significantly (P<0.05), however, somatic cell count decreased significantly (P<0.05) with chelated zinc and manganese supplements. Chelated zinc and manganese supplements improved feed conversion ratio and economic efficiency as well. Likewise, chelated zinc and manganese supplements improved all reproductive traits (first estrus and service, service period, days open, calving interval and number of service per conception and conception rate). In conclusion, chelated zinc and manganese supplements for dairy cows improved digestibility, feed intake, rumen fermentation activity, some blood parameters, milk yield and composition, feed conversion ratio and economic efficiency as well as reproductive traits